High porosity Mo doped BiVO4 film by vanadium re-substitution for efficient photoelectrochemical water splitting

A high porosity Mo doped BiVO4 film was synthesized by excess Mo doping and following vanadium re-substitution, which exhibited great photoelectrochemical performance. [Display omitted] •High porosity structure was constructed via dissolution of excess Mo in BiVO4 film.•The contact area of photoanode and electrolyte is increased.•The VMo-BiVO4 photoanode exhibits great photoelectrochemical performance.•The separation efficiency for VMo-BiVO4 reaches to 96%. Bismuth vanadate (BiVO4) is one of the most studied photoanodes whose photoelectrochemical (PEC) performance is limited by the sluggish charge mobility and substantial recombination losses. Here, a high porosity Mo doped BiVO4 film was synthesized by excess Mo doping and following vanadium re-substitution. The as-prepared BiVO4 based photoanode has large contact area between the electrolyte and the film due to the dissolution of excess Mo, shown by the results of electrochemically active surface area tests. As a result, the photocurrent of VMo-BiVO4 is 6.12 mA/cm2 at 1.23 V vs. the reversible hydrogen electrode (RHE) in 0.2 M KPi + 0.2 M Na2SO3 with the charge separation efficiency of ~96%, and the photocurrent of VMo-BiVO4 (3.18 mA/cm2 at 1.23 V vs. RHE) is 6.91 times of pristine BiVO4 in 0.2 M KPi. This approach demonstrated that a reasonable doping structure design could guarantee PEC water splitting with high performance.